题解

#include<iostream>
using namespace std;
const int N = 1e5+5;
int n,m,a[N],s[N],l,r;
int main(){
	cin >> n >> m;
	for(int i = 1;i<=n;i++){
		cin >> a[i];
		s[i] = s[i-1] + a[i];
	}
	while(m--){
		cin >> l >> r;
		cout << s[r]-s[l-1]<<endl;
	}
	return 0;
}